Super-2s in New Hampshire

[HemiCRZ]

Hello all,

I'm from Mississippi visiting in New Hampshire and I just have a question maybe you all could answer. I've noticed while driving that the super-2 style of limited-access highway is extremely popular here. NH 101, NH 16, and I-93 are just a few that I've driven on, although I've discovered that I-93 was done that way out of necessity to preserve Franconia Notch.

My question is, what makes building a highway with grade-separated interchanges in mostly rural areas so popular here? We do not have any of these in the south whatsoever. In fact, many of our four-lane routes aren't even built to freeway standards, with grade-separated crossings being limited to other four-lane expressways or extremely important state routes.

Do not get me wrong, I enjoy driving on these super-2s, particularly because its interesting to me, but I cannot for the life of me understand the practicality behind constructing all of these grade-separated interchanges for a two-lane route in mostly rural areas.

[Roadgeekteen]

I know I-93 was because of the man of the mountain.

[froggie]

I-93 was moreso because of the upper reaches of the Pemigewasset River plus the narrowness of the Notch adjacent to Echo Lake and Profile Lake.  The Man of the Mountain was a contributing factor, but not the primary factor.

As to Hemi's original question, it's largely because of a desire for access control on the upgraded highways, limiting cross-traffic, plus the general higher tolerance New England has for traffic volumes on 2-lane roadways.  The Deep South, in general, has lower traffic tolerances and thus tends to 4-lane their roadways at lower volume thresholds than New England, nevermind that in the South, it's both more wide open and cheaper to construct such.

It's also worth noting that virtually all of the New Hampshire examples are bypasses of towns (I-93 through the Notch being the notable exception), where it was deemed at the time sufficient for 2 lanes on the bypass.

Another thing about the Deep South is that they tend to have an aversion to upgrading existing routes to limited access, especially in Alabama.  Much of Mississippi's 4-laning projects retain private driveways...only where they went on new alignment did they limit private access.

[HemiCRZ]

I know I-93 was because of the man of the mountain.

That's what I discovered during my research. NHDOT wanted an interstate through the area, environmentalists said a full four-lane facility would disturb the natural beauty of Franconia Notch, so the compromise was to build a two-lane facility.

Don't get me wrong, I drove through Franconia Notch and loved the scenery, and the freeway was not an issue. The fact that I was on a two-lane interstate highway was equally fascinating as the scenery.

What did surprise me since we are on the subject, was the fact that there is not a single I-93 trailblazer from the beginning of Franconia Notch Parkway to Franconia. All exit signs are numbered, but on brown backgrounds. Milemarkers do not feature I-93 shields unlike the milemarkers outside of the Parkway.

[froggie]

What did surprise me since we are on the subject, was the fact that there is not a single I-93 trailblazer from the beginning of Franconia Notch Parkway to Franconia.

Not true...they exist at Exit 34B.  It's a small green unisign with both I-93 and US 3 shields, the directional marker, and a small brown tab underneath with "Franconia Notch Pkwy".  There's also one southbound just south of Exit 34C (NH 18).

[HemiCRZ]

What did surprise me since we are on the subject, was the fact that there is not a single I-93 trailblazer from the beginning of Franconia Notch Parkway to Franconia.

Not true...they exist at Exit 34B.  It's a small green unisign with both I-93 and US 3 shields, the directional marker, and a small brown tab underneath with "Franconia Notch Pkwy".  There's also one southbound just south of Exit 34C (NH 18).

Oh! I never got off at either of those exits so I was completely unaware. I just know that I drove the mainline and was shocked that there was no I-93 shields... almost seemed like NHDOT didn't want to identify this weird two-lane Interstate as an Interstate...

[froggie]

I WAS referring to the mainline.

[DJStephens]

Would suspect the the NH transportation department did plan on eventual "dualization" of most if not all of the super two routes as originally built.  With the exception of the Franconia Notch 93 segment.
Rt 16's four lane section progressed N, and believe all of 101 between 93 and 95 is now divided.   They probably got bogged down with four laning the remainder.   (Laconia, Milford, Keene).   Not an expert on the NH department to know if they preserved ROW along, or on one side of the super two sections for eventual four laning/dualization.  Been away from New England for twenty five years, but remember construction in the Notch in the summer of 1985 for the parkway section of 93.   

[Roadgeekteen]

Any plans to 4 lane the remainder of the Spaulding?

[HemiCRZ]

Would suspect the the NH transportation department did plan on eventual "dualization" of most if not all of the super two routes as originally built.  With the exception of the Franconia Notch 93 segment.
Rt 16's four lane section progressed N, and believe all of 101 between 93 and 95 is now divided.   They probably got bogged down with four laning the remainder.   (Laconia, Milford, Keene).   Not an expert on the NH department to know if they preserved ROW along, or on one side of the super two sections for eventual four laning/dualization.  Been away from New England for twenty five years, but remember construction in the Notch in the summer of 1985 for the parkway section of 93.   

I would suspect that this is the case. Route 101 for example between Wilton and the freeway section in Bedford, all of the stop-lights are configured for four lanes, two in each direction with turn lanes. The route will expand to four lanes briefly before the stoplight, and then go back to two-lanes past the stoplight.

[HemiCRZ]

I WAS referring to the mainline.

I must not have been paying attention 

Update: I do see the sign now. I completely missed it when I was driving through. https://www.google.com/maps/@44.1692499,-71.6828523,3a,75y,334.95h,91.02t/data=!3m6!1e1!3m4!1sNT22rg-kBIMWKkAY8heHdw!2e0!7i16384!8i8192

[Revive 755]

I know it was a compromise, but after seeing I-70 through Glenwood Canyon in Colorado, which keeps four lanes I-93 through Franconia Notch looks like they didn't make much of an effort.  Especially around Mile 108 where there is a large grass median.

[froggie]

On the contrary, there was effort on the part of NHDOT to push a 4-lane corridor through.  One huge difference between Glenwood Canyon and Franconia Notch is that the entirety of the latter has been designated parkland since pre-Interstate.  So major Section 104(f) issues there, unlike Glenwood Canyon.

[3467]

You can add the Midwest to low tolerance of 2 lane traffic.Iowa and Missouri are trying to use passing lanes. Most of the roads under study in Illinois and Iowa have averaged of 3000 to 6000 vpd.

[HemiCRZ]

Some locations down south like to use passing lanes, MDOT for example has several corridors where they would prefer passing lanes over a full divided highway.

I think part of it is lack of funding to secure ROW, and usually the tolerance for traffic is so low that a four-lane road may get built before traffic ever needed a passing lane.

Another concern especially close to the coast in a post-Katrina world, is that building four-lane highways will drastically improve evacuations. I went to Hampton Beach, and was shocked that there was so few routes that led away from the coast, and the few routes that did were all two-lane rural roadways. NH 101 doesn't open up to a full freeway until after it crosses I-95.

Back home in MS, there are at least eight four-lane routes that will take you from the coast to I-10, and at least four major four-lane expressways that will carry you way farther inland.

Mississippi has no issues with building new four-lane highways, what Mississippi has issues with is maintaining those roads after the fact, and building them to substandard specifications with no shoulders, no milemarkers, lackluster exit signage and grade-seperated interchanges, etc. As froggie stated earlier, MS's four-lane system was basically built by slapping down an additional two lanes next to an already established roadway, connecting driveways with crossovers, and letting it go just like that.

If you want an example of how this method fails the traveling public, look at US 49, which is the ONLY divided highway to connect the state capital to the coast. It is riddled with stoplights, traffic, and it seems that instead of correcting these issues, MDOT only wants to focus on adding more stoplights.

[hotdogPi]

I went to Hampton Beach, and was shocked that there was so few routes that led away from the coast, and the few routes that did were all two-lane rural roadways. NH 101 doesn't open up to a full freeway until after it crosses I-95.

Hampton Beach is a tourist destination, not a major city. There won't be hundreds of thousands needing to evacuate from there. (Portsmouth has NH 16, and it's still only about 20,000.)

[SectorZ]

Another concern especially close to the coast in a post-Katrina world, is that building four-lane highways will drastically improve evacuations. I went to Hampton Beach, and was shocked that there was so few routes that led away from the coast, and the few routes that did were all two-lane rural roadways. NH 101 doesn't open up to a full freeway until after it crosses I-95.

Back home in MS, there are at least eight four-lane routes that will take you from the coast to I-10, and at least four major four-lane expressways that will carry you way farther inland.

The difference there is that NH can never even get something remotely as bad as Katrina. The NH coastline is actually likelier to get damaged from autumn-to-spring coastal lows (called nor'easters in New England, as they move to the east of New England and feature northeast surface winds). March 2018 was the last time the coast took a good pounding, and if you drove on 1A in the southern portion of Rye you drove over a couple sections of new pavement that got cleaned out in that storm.

That said, the worst of those nor'easters are honestly little to no concern of residents. Really only people on and along 1A would need evacuating, and it's a really small amount of people as a whole. Seabrook Beach could take off down 286, Hampton Beach down 101, and the other roads (27, 111, numerous unnumbered secondary roads) can withstand the traffic for North Hampton, Rye, and New Castle. I've also never seen any evacuations in my lifetime. Along with that, if they did need evacuating, winter storms tend to be more predictable further out for a variety of reasons.

That said, just because an evacuation for some other reason could be a huge bottleneck someday, 101 would be better off 4 lanes to 1A. If/when they replace the drawbridge between Hampton and Seabrook, since most of the options involve no temporary bridge during replacement, this will really strain 101.